Producing apparatus for wells



Sept. 29, 1964 FENNER, JR

PRODUCING APPARATUS FOR WELLS 5 Sheets-Sheet 1 Filed Feb. 1, 1963 28 FIG. 3

fl. P ATTORNEY Sept. 29, 1964 K. L. FENNER, JR 3,150,604

PRODUCING APPARATUS FOR WELLS F iled Feb. 1, 1963 s Sheets-Sheet 2 FIG. 4 FIG. 5 FIG. 6

ATTORNEY 0 mama/4 4'.

p 29, 1964 r K. L. FENNER, JR 3,150,604

PRODUCING APPARATUS FOR WELLS Filed Feb. 1, 1963 5 Sheets-Sheet 3 III/1111111111.

INVENTOR. KNOLIE L. FENNER, JR.

A TTORNE Y 6. Mbwzm.;.

United States Patent 3,150,604 PRODUCING APPARATUS FOR WELLS Knolie L. Fenner, Jr., Abilene, Tex., assignor to Wayne Petroleum Company, Abilene, Tex., a corporation of Illinois Filed Feb. 1, 1963, Ser. No. 255,465 7 Claims. (Cl. 103-219) This invention relates broadly to well producing apparatus for oil wells and the like and more particularly to a unit whose operation renders it possible to recover a bottom hole fluid pump from a well when the pump plunger or the pump hold-down is stuck, with out the necessity for removing the well tubing string which contains the pump.

According to the invention, a jarring or impact means is arranged between the pump proper and the pump holddown and interconnects these elements in such a manner that the pump, while properly operating, may pump fluid through the hold-down and through the jarring means and into the tubing string above the pump so that the tubing string will become filled with fluid for collection and storage above ground. Should the pump plunger become stuck or inoperable or should the hold-down become stuck within the sealing nipple near the bottom of the tubing string, an upward pull on the sucker rod will serve to release and actuate the jarring means to either release the hold-down from its seat or to cause parting of one portion of the apparatus from the hold-down so that the pump proper and the remaining elements of the unit or apparatus may be readily retrieved without the necessity for pulling the tubing string out of the well casing. Port means are provided in the apparatus to equalize the fluid pressure in the tubing string between the hold-down and jarring means while the latter is operating, thereby eliminating the necessity for lifting a heavy column of fluid and setting up a flowing or washing action by fluid adjacent the hold-down, thereby tending to cleanse the latter of sand or other foreign material which may be tending to bind the hold-down.

Upon successful removal of the entire unit including pump, hold-down and intermediate jarring means from the tubing string, the pump may be serviced above ground and the assembled unit may be readily re-introduced into the tubing string to allow the continuation of production with a minimum waste of time and Without the great expense, labor and fire hazard incident to withdrawing the entire tubing string from the well casing. In cases where the hold-down separates from the remainder of the unit and remains stuck in the tubing, the remainder of the unit including the pump is withdrawn and serviced and may again be lowered into the tubing string with the omission of one part and successfully recoupled with the components including the hold-down which remain within the tubing, and well production may again commence without difliculty and in a minimum time and with minimum labor.

Pump hold-downs are Well known in the art as are jarring devices per se to release well tubing and other stuck objects. The essence of this invention, however, resides in the integrating of a novel and simplified jarring and fluid flowing means with and between the pump proper and the hold-down to allow normal pumping of fluid directly through the entire invention unit when the pump is properly operating and also allowing retrieving of the entire unit or a substantial portion thereof including the pump, as when the pump requires servicing, without the necessity for withdrawing the tubing string from the Well or losing the pump or damaging the sucker rods through excessive tension thereon and with the absolute minimum of time and labor and loss of production in the well and with a great reduction in fire hazard incident to pulling "ice tubing filled with oil from any well. Therefore, the complete combination unit above-discussed and its simplified mode of operation and its combined use as a well production tool, jarring means and retrieving means constitutes the subject matter of the invention sought to be patented.

Oher objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings forming a part of this application and in which like numerals are employed to designate like parts throughout the same,

FIGURE 1 is a fragmentary section through the bottom portion of a well bore hole showing the well casing, tubing string and the invention apparatus within the tubmg string, the parts being arranged to show normal pumping of fluid upwardly through the invention apparatus by the bottom hole pump.

FIGURE 2 is an enlarged central vertical longitudinal section through that portion of the invention apparatus directly below the pump proper during the normal pumpmg operation,

FIGURE 3 is a similar View depicting the operation of the jarring means to unseat the pump hold-down and to equalize fluid pressure within the tubing adjacent the hold-down for cleansing the latter and for ease of unseating,

FIGURE 4 is a fragmentary central vertical section similar to FIGURE 1 and showing the retrieving of the entire invention apparatus after successful operation of the jarring and flow control means,

FIGURE 5 is a similar view showing the retrieving of the pump and portions of the invention apparatus which may part from the hold-down and other apparatus parts as in cases where the hold-down is badly stuck and cannot be jarred loose,

FIGURE 6 is an enlarged fragmentary central vertical longitudinal section showing the invention apparatus including the repaired pump reconnected with the apparatus components which remained in the tubing after the parting of the apparatus depicted in FIGURE 5,

FIGURE 7 is an exploded perspective view of the invention apparatus parts which in use are assembled with and between the hold-down and the pump proper, parts in section, and

FIGURE 8 is an enlarged horizontal transverse section taken on line 8-8 of FIGURE 2.

In the drawings, wherein for the purpose of illustration is shown a preferred embodiment of the invention, the numeral 10 designates a section of casing within a well bore hole and being perforated at 11 adjacent at producing zone 12 of the well. The lowermost portion of a conventional tubing string 13 is shown inside of the casing 10 and this tubing may be perforated at 14 near its bottom end wall 15. The tubing 13 has a reduced diameter seating nipple 16 near and above the perforations 14 for the reception and anchorage of a tubular pump hold-down 17. The hold-down 17 is per se conventional and includes a reduced tubular stem 18 carrying a plurality of spaced fluid sealing rings 19, as shown, having snug engagement within the bore of the nipple 16 to effectively seal this bore when the hold-down is engaged therein. The hold-down 17 has an upper enlarged tubular head 20 integral therewith, carrying a top reduced screw-threaded extension 21. A tapered shoulder 22 at the bottom of the head 20 is adapted to engage a similarly tapered seat 23 at the top of nipple 16.

A bottom hole pump 23 of conventional construction is spaced above the hold-down 17 within the tubing string 13 and includes the usual pump plunger 24, disposed inside of a pump barrel or tube 25 and connected with and adapted to be reciprocated by a sucker rod 26. The sucker rod 26 operates through an opening in the head 27 C9 of the conventional pump barrel. The mode of operation of the bottom hole fluid pump is well known in the art and need not be dealt with in detail herein.

A further tubing section 28 is connected with the pump barrel by a conventional screw-threaded joint 29 and in effect forms a depending continuation of the pump barrel. In turn, the lower end of tube 28 has a screwthreaded connection at 30 with a relatively short sleeve or tube 31 having an upper screw-threaded neck 32 integral therewith, FIGURE 2. Near and above the lower end of sleeve 31, the same has an internal annular groove or recess 33 for the reception of a resilient split locking ring 34 in the assembled apparatus. The lower annular edge 35 of groove 33 is conically tapered as shown in the drawings, whereas the upper edge 36 of the groove is cut square with the axis of the sleeve 31. By virtue of this construction, upward axial movement of the sleeve 31 may cause contraction or closing of the split locking ring 34 and disengagement thereof from the sleeve 31, as will be further described. The lower end or mouth 37 of the sleeve bore is also preferably beveled as shown.

A tubular connector and sealing member 38 is provided intermediate the pump hold-down 17 and the sleeve 31. The member 38 has an enlarged internally screwthreaded head 39 at its lower end, having screw-threaded engagement with the extension 21 of the pump hold-down. The member 38 further includes a reduced diameter portion 40 engaging telescopically within the bore of sleeve 31 and carrying near and above the head 39 a pair of fluid sealing rings 41 to seal the lower portion of the sleeve bore immediately below the locking ring 34. The upper end portion 42 of tubular member 38 is screwthreaded for connection with an internally screw-threaded connector fitting 43 disposed movably within the bore of the sleeve 31. A reduced diameter external annular groove 44 is formed upon the member 38 adjacent the locking ring 34 by the lower end of fitting 43 and a shoulder 45 on the tubular member 33. The locking ring 34 while in the normal expanded or locking condition has a radial wall thickness causing it to lie within the adjacent internal and external grooves 33 and 44 as shown clearly in FIGURE 2. In such position, the ring 34 looks the sleeve 31 and associated elements against axial movement relative to the member 38 and associated elements.

A jarring and fluid flow control tube 46 extends within the sleeve 31 and tubing section 28 above the tubular member 38 with its bore in direct communication with the bore of the latter. The lower end 47 of tube 46 is screwthreaded for connection with connector fitting 4-3, as shown. The wall thickness of the tube 46 at the top of fitting 43 is relatively thin and frangible so that the tube 46 may part under certain conditions of tension and impact to be further described and illustrated in FIGURES 5 and 6.

The tube 46 has an enlarged jarring head 48 at its upper end providing a shoulder 49 engageable with the upper end 50 of sleeve 31 during the jarring operation as depicted in FIGURE 3. The tube 46 has a plurality of side wall ports 51 arranged preferably as shown in the drawings and spaced longitudinally and circumferentially of the tube.

With the apparatus fully assembled as best shown in FIGURE 2 and with the ring 34 in looking engagement with sleeve 31 and tubular member 38, the sealing rings 41 provide a fluid seal between the interior of the sleeve 31 and the bore of Well tubing string 13.

Assuming that the well casing 10 and tubing string 13 are in place within the well bore hole, FIGURE 1, the entire invention apparatus assembly above-described is lowered into the tubing string suspended from sucker rod 26 and this apparatus includes the bottom hole pump, the pump hold-down or anchor 17, and the intermediate locking, jarring and flow control elements shown particularly in FIGURE 2. The weight of the assembly is sufficient to force the compressible fluid sealing rings 19 into tight sealing engagement with the bore of nipple 16 and the beveled shoulder 22 engages the beveled seat 23' at the top of the nipple. The parts of the apparatus now remain in their described assembled relationship and the sucker rod 26 is operated from above ground in a well known manner to cause reciprocation of the pump plunger 24 and pumping of fluid upwardly through the tubing string 13 until such string overflows and the fluid is collected and stored above ground.

During this normal pumping, the sealing rings 19 and 41 are active and fluid from the formation 12 enters the bottom of the tubing string through the perforations 14 and flows upwardly through the open bore of hold-down 17 and through the open bores of tubular member 38 and tube 46 and above the pump and into and upwardly through that portion of the tubing string which extends above the invention apparatus. At this time, no fluid can pass downwardly through the seals 41. The normal pumping operation may continue indefinitely.

When it is required to withdrawn the bottom hole pump from the well for servicing, as when the pump plunger is stuck or for some similar reason, an upward pull is exerted through the sucker rod 26 and in some cases, the pump hold-down 17 may be dislodged rather easily from the nipple 16 and the entire invention apparatus may be withdrawn from the tubing string while the locking ring 34 remains in the locking position, FIG- URE 2.

More often than not, the hold-down 17 will be rather tightly stuck within the bore of nipple 16 because of the normally tight friction fit, the eflects of corrosion, and accumulations of sand and the like in the region of the hold-down. In these instances, the lifting force through sucker rod 26 will be insutiicient to dislodge the holddown 17 without the aid of some impact or jarring force in the upward direction. Also, it is desirable never to injure the sucker rods by excessive tension thereon. To take care of these factors and to dislodge the stuck holddown 17, the upward pull transmitted through the pump barrel 25, tube section 28 and sleeve 31, will cause the tapered shoulder 35 to close the split locking ring 34 and shift it further into the groove 44 and thereby separate it from the internal groove 33 to unlock the sleeve 31 and associated parts from the tubular member 38. When this .occurs, the sleeve 31, tube section 28 and the pump barrel will shift upwardly, FIGURE 3, and the top end 50 of sleeve 31 will strike the shoulder 49 of tube 46 and an upward jarring force will be transmitted through the tube 46, fitting 43 and tubular member 38 to the hold-down 17 with which these elements are directly connected. Repeated jarring of the hold-down in this manner will usually dislodge it from the nipple 16 as depicted in FIGURE 3 and if this operation is successful, the entire apparatus including pump, hold-down and all intermediate parts may be withdrawn from the tubing string while in the unlocked or open condition as shown in FIGURE 4.

During the described jarring operation and immediately after the locking ring 34 releases the sleeve 31 from the member 38, the sealing rings 41 pass out of the bore of sleeve 31 and this bore is in open communication with the interior of the tubing string 13, FIGURE 3. This has the effect during the jarring operation of equalizing the pressure of the column of fluid in the tubing string 13 so that the jarring operation will not necessitate the lifting of the entire column of fluid above the apparatus. That is to say, when the sleeve 31 is initially unlocked from the member 38, the fluid in the tubing string may flow back into the formation 12 through the ports 51 of tube 46 as shown by the arrows in FIGURE 3. Fluid may also flow at this time downwardly through the main bore of tube 46 and through the bore of member 38 back to the formation 12. Fluid in the tubing string 13 also passes downwardly in the annular space 52, FIGURE 3, between the sleeve 31 and tubing string so that such fluid may enter the ports 51, as stated. This equalizing of the pressure of the column of fluid in the tubing string 13 has a two-fold effect. The velocity of the equalizing fluid tends to wash away sand or other foreign material deposits or sediments which may be present near the top of the pump hold-down 17 and this will further facilitate unseating of the hold-down during succeeding jarrings thereof. Secondly, by equalizing the fluid pressure, the weight exerted on the hold-down 17 by the fluid column in the tubing string is reduced, thereby requiring less impact and fewer impact blows to dislodge the hold-down.

It is desired to re-emphasize here that the apparatus functions as described to equalize or neutralize the effect of the fluid column during the jarring operation and the apparatus additionally allows the pumping of fluid directly therethrough while in the assembled and locked position shown in FIGURES l and 2. Known prior art jarring tools do not allow the pumping or flowing of fluid therethrough and such tools in the prior art are not placed below the bottom hole pump or between this pump and the pump hold-down and are not interconnected therewith to form a unitary assembly of pump, hold-down and jarring and flow regulating means. It is this combination and its simplified and efllcient mode of operation which renders the invention apparatus highly successful and effects great economies in the operation or producing of Wells.

As shown particularly in FIGURES 5 and 6, the invention has additional important features of operation. If the hold-down 17, FIGURE 5, is unusually difficult to dislodge from the nipple 16 and it is desired not to strain the sucker rod 26, the tube 46 is designed to fail or part at or near its screw-threads 47 previously decribed. This parting or failure of the tube 46 will occur at the weakest point of the tube under the impact force against the tube shoulder 49 by sleeve 31. When this tube failure occurs, FIGURE 5, the pump proper together with tube section 28, sleeve 31 and a portion of tube 46 may readily be lifted as a unit from the tubing string 13, as shown. The hold-down 1'7, tubular member 38 and associated elements including locking ring 34 and a lower portion of fractured tube 46 remain in the bottom of the well tubing and within the nipple 16, FIGURE 5.

After completion of servicing of the pump above ground, the withdrawn invention components minus the tube 46 may be re-introduced as a unit into the tubing string, FIGURE 6, and the sleeve 31 is telescoped over the fractured tube portion 46 remaining in the well and over the locking ring 34 and associated parts and the apparatus is easily returned to its initial locked or closed condition for further regular pumping in the manner originally described in connection with FIGURES 1 and 2 but without the tube 46 being replaced. This procedure eflects a fluid seal between the well tubing and the pump proper by re-engagement of the sealing rings 41 with the bore of sleeve 31, FIGURE 6, and in effect, a second pump and pump hold-down assembly has been achieved without removing the originally stuck hold-down 17 and without the necessity for the dangerous removal of the tubing string 13 from the well.

The use of the invention apparatus in any of the ways above-described is entirely practical, eflicient and economical. The invention apparatus is extremely versatile therefore in its capabilities and successfully overcomes a very diflicult and perplexing problem concerning the retrieving of stuck bottom hole pumps from wells without injuring the sucker rods .or losing the pump in its entirety.

A minor modification of the apparatus may be utilized to eliminate the feature of breaking the frangible tube 46. Instead, the screw-threads 47 of the tube 46 may be formed as left-hand screw-threads, whereby turning of the sucker rod string in the direction for tightening the other joints of the apparatus will actually loosen and detach the tube 46 from the fitting 43, thus making it unnecessary to fracture the tube by impact.

Another minor modification not shown in the drawings resides in the provision of additional fluid sealing rings between the bore of sleeve 31 and the tube 46, just above the screw-threads 47 to further guarantee against the entry of foreign material into the moving components while the apparatus is in the closed position, FIGURE 2.

It is to be understood that the form of the invention herewith shown and described is to be taken as a preferred example of the same, and that various changes in the shape, size and arrangement of parts may be resorted to, without departing from the spirit of the invention or scope of the subjoined claims.

Having thus described my invention, I claim:

1. In producing apparatus for wells, a bottom hole pump having a pump barrel and a reciprocatory plunger adapted for connection with a sucker rod, a tubular pump hold-down element below said pump and remote from the pump and adapted for anchorage within a nipple of well tubing, extension tube means interconnecting the pump barrel and said tubular hold-down element and forming therewith a through passage for fluid so that fluid may be lifted in said well tubing by said pump upon reciprocation of said plunger, axially spaced relatively movable rigid impact parts on said extension tube means operable by reciprocation of said sucker rod to dislodge said hold-down element from said nipple, resilient means on said extension tube means to normally lock said impact parts in axially spaced non-moving relation and yielding in response to a predetermined tension on said sucker rod to release said impact parts for relative movement and then allowing axial extension of the extension tube means, fluid sealing means on the extension tube means actively sealing the same above the holddown element when said resilient means is active to lock said impact parts in said spaced non-moving relation and becoming inactive upon said release of said impact parts, said extension tube means having fluid port means which upon release of said impact parts and said relative movement thereof eflects balancing of fluid pressure adjacent the extension tube means to allow easy reciprocation of the sucker rod for causing said relative movement of the impact parts.

2. A readily retrievable bottom hole fluid pumping unit for wells comprising in combination a pump barrel, a reciprocatory pump plunger within said barrel adapted for connection with a sucker rod, a tubular pump holddown element spaced below and remote from the pump barrel and adapted for anchorage within a nipple of well tubing containing said unit, extension tubing between and interconnecting the pump barrel and hold-down element and forming therewith a through passage for fluid so that fluid may be elevated by reciprocation of said plunger, said extension tubing including telescopically interfitting inner and outer tubing parts, said inner tubing part having radial fluid ports, fluid sealing means between said inner and outer tubing parts to seal the same above said hold-down element when said parts are substantially telescoped, resilient locking means on said inner and outer tubing parts normally locking the same in telescoped relation and yielding to unlock said parts and allow axial extension thereof responsive to a predetermined tension on said sucker rod, said axial extension of said parts uncovering said sealing means and rendering the same inactive and allowing said fluid ports to balance fluid pressure adjacent said extension tubing, a first impact element on said inner tubing part near the top thereof, and a coacting second impact element on the outer tubing part spaced below the first impact element when said tubing parts are telescoped, locked and sealed and freely shiftable by reciprocation toward and away from the first impact part when said tubing parts are unlocked and unsealed.

3. A bottom hole pumping unit for wells comprising a pump barrel and a pump plunger therein adapted for connection with a sucker rod, a pump hold-down adapted for anchorage Within a well tubing string, a tubular memher secured to the hold-down extending thereabove and having a through bore and side ports and an impact shoulder near the top thereof, exterior sleeve means surrounding said tubular member and secured to the pump barrel and depending therefrom and having fluid sealing engagement with the tubular member near the bottom of the sleeve means, said sleeve means having an internal impact shoulder normally spaced from and axially opposed to the first-named impact shoulder, and axial tension force responsive releasable blocking means for the sleeve means and said tubular member normally locking them against relative axial movements with said shoulders separated, said locking means comprising a split resilient ring intermediate the sleeve means and tubular member above said sealing engagement, said sleeve means and tubular member having companion grooves accommodating said ring, and a camming face on said sleeve means engageable with said split ring to contract the same and release the sleeve means from looking engagement with the tubular member upon the application of a suificient lifting force through the sleeve means.

4. A bottom hole pumping unit for wells which is readily retrievable, comprising a pump barrel, a reciprocatory plunger within said barrel adapted for connection with a reciprocatory sucker rod, a tubular holddown element below the pump barrel and remote therefrom and adapted for anchorage within a nipple of a tubing string, telescopic extension tubing extending between the pump barrel and said hold-down element including outer tubing secured to said barrel and inner tubing secured to said hold-down element, fluid sealing means between said inner and outer tubing and being active when the inner and outer tubing are telescoped and inactive when the inner and outer tubing are extended axially, said inner tubing having fluid pressure balancing side ports rendered active by the axial cxtension of the inner and outer tubing and the de-activating of said fluid sealing means, releaseable locking means on the inner and outer tubing normally locking the same in telescoped relation with the sealing means active and said side ports inactive and unlocking the inner and outer tubing for relative axial movement responsive to a predetermined tension on said sucker rod, and axially spaced coacting opposed impact parts on said inner and outer tubing for jarring said hold-down element from said nipple by relative reciprocation of said inner and outer tubing.

5. A bottom hole pumping unit for wells comprising a pump barrel, a plunger within said barrel adapted for connection with a reciprocatory sucker rod, a tubular hold-down element below the pump barrel and remote therefrom and adapted for anchorage within a nipple of well tubing, telescopic extension tubing interconnecting the pump barrel and hold-down element and form ing therewith a through passage for fluid, means to releasably lock said extension tubing in telescoped relation and automatically releasing said tubing for relative movement axially upon the application of sufiicient tenison to the sucker rod, said extension tubing having interengaging fluid seal means active only when the tubing is locked and inactive when the tubing is unlocked and extended axially, said tubing having fluid pressure bypass means effective only when said seal means is inactive, and axially spaced impact means on said tubing operable to dislodge the hold-down element during axial extension and retraction of said tubing by the sucker rod after said unlocking of the tubing.

6. The invention as defined by claim 2, and wherein said inner and outer tubing parts are formed in sections, and screw-threaded joints connecting said sections, at least one of said screw-threaded joints separable by turning the screw-threads thereof in an opposite direction from that required to separate the other joints.

7. A bottom hole fluid pumping unit for wells comprising in combination a tubular pump barrel, a reciprocatory plunger within said barrel adapted for connection with a sucker rod, a tubular pump hold-down element adapted for anchorage within a nipple of a well tubin string below the pump barrel, 21 depending pump barrel extension, a further depending sleeve secured to said extension, a tubular member of reduced diameter secured to the top of the hold-down and interfitting telescopically within the bore of the sleeve and said extension and having side ports and an impact part, said sleeve having a coacting impact part normally separated from the first-mentioned impact part, fluid sealing means between the bore of said sleeve and tubular member near the lower end of the sleeve, said sleeve and tubular member having respectively internal and external grooves above said sealing means, and a resilient locking ring within said grooves normally locking said sleeve and tubular member against relative axial movement and releasable under a known degree of tension on the sucker rod to allow relative axial movement between the sleeve and tubular member and said impact parts for dislodging said hold-down, said sealing means then becoming inactive and said ports then serving to equalize fluid pressure above said hold-down.

References Cited in the file of this patent UNITED STATES PATENTS 663,029 Horsley Dec. 4, 1900 2,070,135 Laughinghouse Feb. 9, 1937 2,572,388 Redpath Oct. 23, 1951 

1. IN PRODUCING APPARATUS FOR WELLS, A BOTTOM HOLE PUMP HAVING A PUMP BARREL AND A RECIPROCATORY PLUNGER ADAPTED FOR CONNECTION WITH A SUCKER ROD, A TUBULAR PUMP HOLD-DOWN ELEMENT BELOW SAID PUMP AND REMOTE FROM THE PUMP AND ADAPTED FOR ANCHORAGE WITHIN A NIPPLE OF WELL TUBING, EXTENSION TUBE MEANS INTERCONNECTING THE PUMP BARREL AND SAID TUBULAR HOLD-DOWN ELEMENT AND FORMING THEREWITH A THROUGH PASSAGE FOR FLUID SO THAT FLUID MAY BE LIFTED IN SAID WELL TUBING BY SAID PUMP UPON RECIPROCATION OF SAID PLUNGER, AXIALLY SPACED RELATIVELY MOVABLE RIGID IMPACT PARTS ON SAID EXTENSION TUBE MEANS OPERABLE BY RECIPROCATION OF SAID SUCKER ROD TO DISLODGE SAID HOLD-DOWN ELEMENT FROM SAID NIPPLE, RESILIENT MEANS ON SAID EXTENSION TUBE MEANS TO NORMALLY LOCK SAID IMPACT PARTS IN AXIALLY SPACED NON-MOVING RELATION AND YIELDING IN RESPONSE TO A PREDETERMINED TENSION ON SAID SUCKER ROD TO RELEASE SAID IMPACT PARTS FOR RELATIVE MOVEMENT AND THEN ALLOWING AXIAL EXTENSION OF THE EXTENSION TUBE MEANS, FLUID SEALING MEANS ON THE EXTENSION TUBE MEANS ACTIVELY SEALING THE SAME ABOVE THE HOLDDOWN ELEMENT WHEN SAID RESILIENT MEANS IS ACTIVE TO LOCK SAID IMPACT PARTS IN SAID SPACED NON-MOVING RELATION AND BECOMING INACTIVE UPON SAID RELEASE OF SAID IMPACT PARTS, SAID EXTENSION TUBE MEANS HAVING FLUID PORT MEANS WHICH UPON RELEASE OF SAID IMPACT PARTS AND SAID RELATIVE MOVEMENT THEREOF EFFECTS BALANCING OF FLUID PRESSURE ADJACENT THE EXTENSION TUBE MEANS TO ALLOW EASY RECIPROCATION OF THE SUCKER ROD FOR CAUSING SAID RELATIVE MOVEMENT OF THE IMPACT PARTS. 